Zeolites are crystalline aluminosilicate compositions which are microporous and which have a three-dimensional oxide framework formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure.
The number of synthetic zeolites is well over a hundred as evidenced by the Atlas of Zeolite Structure Types published by the International Zeolite Association (IZA). As is well known, zeolites are distinguished from each other on the basis of their composition, crystal structure and adsorption properties. One method commonly used in the art to distinguish zeolites is x-ray diffraction.
U.S. Pat. No. 6,613,302 discloses UZM-5, UZM-5P and UZM-6 as examples of a new family of crystalline aluminosilicate zeolites. Zeolites of this family are represented by the empirical formula:Mmn+Rrp+Al(1-x)ExSiyOz where M is an alkali or alkaline earth metal such as lithium and strontium, R is a nitrogen containing organic cation such as tetramethyl ammonium and E is a framework element such as gallium. They are also characterized by unique x-ray diffraction patterns and have catalytic properties for carrying out various hydrocarbon conversion processes.
U.S. Pat. No. 6,388,157 discloses a process for alkylation of aromatic compounds using a new family of related crystalline aluminosilicate zeolites represented by the empirical formula:Mmn+Rrp+Al(1-x)ExSiyOz where M is an alkali or alkaline earth metal such as lithium and strontium, R is a nitrogen containing organic cation such as tetramethyl-ammonium and E is a framework element such as gallium.
U.S. Pat. No. 7,578,993 discloses a process for preparing crystalline aluminosilicate compositions involving preparing a charge density mismatch reaction mixture comprising sources of aluminum, silicon, optionally an E metal and at least one charge density mismatch (CDM) template. The CDM template is an organic nitrogen containing template, in the hydroxide form, e.g. tetraethylammonium hydroxide and is characterized in that it is incapable of inducing crystallization. To this mixture there is added a solution comprising a second templating agent termed a crystallization template (CT). The CT can be an organic template different from the CDM template, an alkali metal, an alkaline earth metal and mixtures thereof.